Unless otherwise stated pictures in this paper are from the reference collection by C.B. de Jong.
Terminology of epidermis features is from Watson, L., and Dallwitz, M.J. 1992 onwards.
In microhistological diet analysis of herbivores, epidermis and/or cuticle fragments of plants and sometimes animals are used for identification. Identifying and measuring 100 fragments of at least 0.01 mm2 in 20 transects gives a quantitative estimate of at least 5% of the total ingested dry matter (Stewart, 1967). Fragments measuring under 0.01 mm2 cannot be used as in many species they do not show sufficient significant details (Van der Steege, 1981; Buil, 1982).
Epidermis fragments of dry fruits are found in several layers, measuring them can give a very rough indication of ingested dry fruit matter.
Diet analysis of herbivores and omnivores
Fragments that are useless for diet analysis:
- Animal fragments in herbivore dung: hairs or feathers of the same species, Arthropod fragments ingested with plants, fragments of dung beetles, etc.
- Plant material picked up with food plants: grass anthers and awns, dead conifer needles,
internal tissue of food plants (most plant parenchyma, xylem vessels).
Fragments that can give an indication of diet composition:
- Plant fragments measuring under 0.01 mm2, including loose hairs and glands.
- Specific parenchyma cells e.g. arm cells.
- Secondary xylem (wood splinters, can be counted).
- Secondary cork (tree bark, fragments can be counted).
- Hairs or feathers of prey animals in omnivorous species (can be scored).
Fragments to be used for a very rough quantitative analysis:
- Corky outside of seeds and dry fruits: measuring all layers found
- Invertebrate epidermis and cuticle (omnivorous rodents!)
Fragments to be used for quantitative diet analysis:
- Buds and thin woody twigs: corky epidermis.
- Leaves, stems and juicy fruits: epidermis and cuticle.
In herbivore diets, plant fragments are the food to be identified. However, some insects will be ingested and also hairs or feathers of the animals themselves. In diets of omnivorous animals, like rodents, small invertebrates are more common and have to be taken into account as diet components.
Animal hairs and insect cuticles can look deceptively like plant epidermis:
In faeces of omnivorous or carnivorous Arthropod cuticles are diet components and can be counted and measured as plant cuticles. Hairs or feathers of prey animals can be scored.
Plant fragments that cannot be used for diet analysis
Anthers can be recognized as such but show a very similar pattern and cannot be identified further than dicot or monocot. Grass anthers (and awns) break off easily and spread all over the vegetation.
Plant fragments that can give an indication of diet composition
Inner tissue fragments of plants > use as indication, count or ignore
Counting of wood splinters can be used as an indication for the thickness of browsed branches.
Vascular tissue, parenchyma, trichome > use as indication or ignore
Cork-like fragments that consist of many layers (tree bark or mesocarp of dry fruits)
> tree bark: count or ignore
Parenchym cells with large intercellular spaces occuring in graminoids growing in marshes
Fragments to be used for a rough quantitative analysis
Fruit mesocarp, e.g. oak > measure
The key for quantitative diet analysis
Plant tissue fragment consisting of one closed layer of cells (epidermis)
- Epidermis fragment at least 0,01 mm2 > 2
- – Epidermis cells not differentiated from inner tissue, all cells contain chloroplasts or hyaline cells are positioned between cells containing chloroplasts > BRYOPHYTA
– Epidermis cells differentiated from inner tissue > 3
- – Walls of epidermis cells thin or thick, not corky. Epidermis cells arranged more or less parallel > 4
– Walls of epidermis cells corky, cells arranged more or less parallel, cells more or less isodiametric > Bud scale or stem of woody dicot, exocarp of hard-walled fruit
– Cells arranged in another way > 9
- – Most cells elongate. Shorter cell walls at a short angle to longer walls > Stem or vein of broad-leaved plant, leaf cushion of gymnosperm, fruit of dicotyledon
– Shorter cell walls more or less at a right angle to the long axis of the cells > Leaves of gymnosperms, monocots or dicots with linear leaves > 5
- – Guard cells of stomata more or less level with other epidermis cells > monocots or dicots with linear leaves > 6
- – Stomata paracytic (subsidiary cells parallel with guard cells) > 7
– Subsidiary cells arranged differently or no clear subsidiary cells present > 8
- – Between the long epidermis cells short cells (cork cells, silica cells, hairs) are placed in a regular pattern; single, in pairs or rows; guard cells of stomata dumbbell-shaped > Poaceae
– No short cells between the long ones, guard cells not dumbbell-shaped > 8
- – Cells containing conical silica bodies in costal or short intercostal rows > Cyperaceae
– Silica crystals in cell walls > Equisetaceae
– No silica cells present > Acoraceae, Aloaceae, Amaryllidacae, Asparagaceae, Dracaenaceae, Juncaceae (no pictures), Juncaginaceae, Typhaceae
- Cells not arranged parallel, usually isodiametric. Epidermis cells more or less thin-walled, cell walls straight, bent or wavy > leaf of dicotyledon, fern or broad-leaved monocotyledon
- – Plastids only present in guard cells of stomata > leaf of dicotyledon or some monocotyledoneous families
– Plastids present in all epidermis cells > leaf of ferns– Cells thick-walled, square or angular, same size or smaller than stomata > Arecaceae
- Buil, M., 1982. Een vergelijking tussen rumeninhoud en faecesanalyse m.b.t. de dieetsamenstelling van één paardantiloop (Hippotragus equinus koba, Gray 1872). Vakgroep Natuurbeheer. Verslag no. 659, Landbouwhogeschool, Wageningen.
- Reinders, E., 1957. Leerboek der Algemene Plantkunde I. Scheltema & Holkema N.V., Amsterdam.
Stace, C.A., 1965. Cuticular studies as an aid to plant taxonomy. Bull. B. M. (N. H.) Bot. 4: 1-78.
- Stewart, D. R.M. 1967. Analysis of plant epidermis in faeces: a technique for studying the food preferences of grazing herbivores. Journal of Applied Ecology 4, 83-111
- Van der Steege, J.G., 1982. Voedselkeuze van een aantal herbivoren in West-Afrika, bepaald d.m.v. faecesanalyse: techniek en resultaten. Vakgroep Natuurbeheer, Verslag nr. 728. Landbouwhogeschool Wageningen.
- Metcalfe, C.R., Chalk, L., 1957. Anatomy of the dicotyledous leaves, stem and wood in relation to taxonomy with notes on economis uses. Oxford University Press, 2 vol.
- Watson, L., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 23rd April 2010. http://delta-intkey.com